Techno-economic anaerobic co-digestion feasibility study for two-phase olive oil mill pomace and pig slurry

Abstract

a b s t r a c tAnaerobic mono-(AmoD) and co-digestion (AcoD) of two-phase olive oil mill pomace (TPOP) and pig slurry (PS) at different ratios were studied in a semi-continuous stirred tank reactor (sCSTR) at mesophilic temperature (37 C). The methane yields for AcoD experiments ranged from 150.9 to 274.3 L CH 4 kg VS À1 d À1 . The maximum chemical oxygen demand (COD) removal rate (59.60%) was achieved for TPOP/PS 80:20 w/w substrate composition at OLR 3.68 g VS L reactor À1 d À1 and 24 days HRT. Despite the energy production from food waste is not a new process, the industrial implementation and application continue to be a challenge. Hence, the present paper also reports on the economic feasibility study of a full scale anaerobic co-digestion plant to treat 7000 t year À1 and 1750 t year À1 of TPOP and PS, respectively. The results of this study are compared against a conventional PS mono-digestion plant. Net present values (NPV) and payback time periods (PBT) were reported to be 782,493 V and 135,701 V and 6.7 and 9.2 years for AcoD and AmoD plants, respectively. Finally, the sensibility analysis concluded that AcoD configuration is less dependent on energy and compost sale prices variations.

Exploitation alternatives of olive mill wastewater: production of value-added compounds useful for industry and agriculture

“…However, numerous obstacles still need to be overcome such as growth inhibition of methanogenic archaea by phenolic compounds, low pH, low nitrogen concentration, etc. (Orive et al, 2016). Other biological alternatives are aerobic methods and include composting as well as treatments with fungi, bacteria, and algae (Pinto et al, 2003;Dhouib et al, 2006;Tziotzios et al, 2007;Chowdhury et al, 2013).…”

Olive‐derived biomass as a source of energy and chemicals

“…Co‐digestion has been proven to increase productivity because of a favorable balance of nutrients . Based on the experimental results obtained in a semi‐continuous stirred tank reactor, the authors concluded that positive net present values (NPVs), an internal rate of return higher than the discount rate and relatively short payback periods can be attained . In another work on anaerobic digestion using olive pomace and olive waste water, an Energy Sustainability Index was calculated as the ratio between the energy produced and spent to produce chemical products used in several pre‐treatment processes that olive residues were submitted to before anaerobic digestion.…”

Zeytin Karasuyunun Anaerobik Arıtılabilirliği ve Biyogaz Üretim Potansiyelinin Araştırılması

“…Bununla birlikte, asidik bir pH değerine sahip olması, düşük alkalinite, düşük azot içeriği, zeytin çekirdeği ve meyvesinin işlenmesi neticesinde oluşan fenolik bileşikler ve lipit fraksiyonlarının varlığı gibi çeşitli ZK özellikleri, bu atıksuyu potansiyel toksik bir substrat haline getirir ve sonuç olarak bu durum anaerobik biyosistem için uygun değildir. Bu sorunların üstesinden gelmek için çeşitli sentetik besin maddeleri, kimyasal ilaveler ve su ile seyreltilmesinin yanı sıra ön işlem uygulamalarının (kimyasal ve biyokimyasal) ZK'nın anaerobik olarak arıtılmasını mümkün kıldığı bildirilmiştir [31,32,[36][37][38][39]. Bununla birlikte, ön arıtma işlemleri genellikle metanojenik aktiviteyi yavaşlattığı bilinmekte ve arıtma maliyetlerinin artmasına sebep olmaktadır [39].…”